Solar battery

ABSTRACT

A solar battery includes a first electrode, a second electrode, a solar cell, an insulating layer and a gate electrode. The solar cell includes a semiconductor structure, a carbon nanotube and a transparent conductive film. The semiconductor structure includes a P-type semiconductor layer and an N-type semiconductor layer and defines a first surface and a second surface. The carbon nanotube is located on the first surface of the semiconductor. The transparent conductive film is located on the second surface of the semiconductor. The transparent conductive film is formed on the second surface by a depositing method or a coating method.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims all benefits accruing under 35 U.S.C. § 119 fromChina Patent Application No. 201710374694.9, filed on May 24, 2017, inthe China Intellectual Property Office, the contents of which are herebyincorporated by reference.

FIELD

The present disclosure relates to a solar battery.

BACKGROUND

A heterojunction is an interface region formed by a contact of twodifferent semiconductor materials. According to the conductivity typesof different semiconductor materials, the heterojunction can be dividedinto homogeneous heterojunction (P-p junction or N-n junction) andheterotypic heterojunction (P-n or p-N). A heterostructure can be formedby multilayer heterojunctions. The heterostructure can be used insemiconductor element and solar battery.

BRIEF DESCRIPTION OF THE DRAWINGS

Implementations of the present technology will now be described, by wayof example only, with reference to the attached figures, wherein:

FIG. 1 is a structure schematic view of one embodiment of a solarbattery.

FIG. 2 is a side structure schematic view of the solar battery in FIG. 1according to one embodiment.

FIG. 3 is a side structure schematic view of the solar battery in FIG. 1according to another embodiment.

FIG. 4 is a structure schematic view of one embodiment of a solarbattery.

DETAILED DESCRIPTION

The disclosure is illustrated by way of example and not by way oflimitation in the figures of the accompanying drawings in which likereferences indicate similar elements. It should be noted that referencesto “another,” “an,” or “one” embodiment in this disclosure are notnecessarily to the same embodiment, and such references mean “at leastone.”

It will be appreciated that for simplicity and clarity of illustration,where appropriate, reference numerals have been repeated among thedifferent figures to indicate corresponding or analogous elements. Inaddition, numerous specific details are set forth in order to provide athorough understanding of the embodiments described herein. However, itwill be understood by those of ordinary skill in the art that theembodiments described herein can be practiced without these specificdetails. In other instances, methods, procedures, and components havenot been described in detail so as not to obscure the related relevantfeature being described. Also, the description is not to be consideredas limiting the scope of the embodiments described herein. The drawingsare not necessarily to scale, and the proportions of certain parts havebeen exaggerated to illustrate details and features of the presentdisclosure better.

Several definitions that apply throughout this disclosure will now bepresented.

The term “substantially” is defined to be essentially conforming to theparticular dimension, shape, or other feature which is described, suchthat the component need not be exactly or strictly conforming to such afeature. The term “comprise,” when utilized, means “include, but notnecessarily limited to”; it specifically indicates open-ended inclusionor membership in the so-described combination, group, series, and thelike.

Referring to FIG. 1, one embodiment is described in relation to a solarbattery 100. The solar battery 100 includes a carbon nanotube 102, asemiconductor structure 104 and a transparent conductive film 106. Athickness of the semiconductor structure 104 ranges from 1 nanometer toabout 1000 nanometers. The semiconductor structure 104 has a filmstructure defining a first surface 1042 and a second surface 1044. Thefirst surface 1042 and the second surface 1044 are two oppositesurfaces. The carbon nanotube 102 is oriented along a first directionand located on the first surface 1042. In one embodiment, there is onlyone carbon nanotube 102 located on the first surface 1042. Thetransparent conductive film 106 is located on the second surface 1044.The semiconductor structure 104 is sandwiched between the carbonnanotube 102 and the transparent conductive film 106. In one embodiment,the solar battery 100 consists of the carbon nanotube 102, thesemiconductor structure 104 and the transparent conductive film 106.

The carbon nanotube 102 is used as a back electrode of the solar battery100. The carbon nanotube 102 is a metallic carbon nanotube. The carbonnanotube 102 can be a single-walled carbon nanotube, a double-walledcarbon nanotube, or a multi-walled carbon nanotube. A diameter of thecarbon nanotube 102 can range from about 0.5 nanometers to about 150nanometers. In one embodiment, the diameter of the carbon nanotube 102ranges from about 1 nanometer to about 10 nanometers. In anotherembodiment, the carbon nanotube 102 is a single-walled carbon nanotube,and the diameter of the carbon nanotube 102 is in a range from about 1nanometer to about 5 nanometers. In one embodiment, the carbon nanotube102 is a metallic single-walled carbon nanotube, and the diameter of thecarbon nanotube 102 is about 1 nanometer.

The semiconductor structure 104 can be a two-dimensional structure. Thesemiconductor structure 104 includes a P-type semiconductor layer 104 aand an N-type semiconductor layer 104 b. The P-type semiconductor layer104 a and the N-type semiconductor layer 104 b are overlapped with eachother. Referring to FIG. 2, in one embodiment, the first surface 1042 ofthe semiconductor structure 104 is a surface of the P-type semiconductorlayer 104 a, the second surface 1044 of the semiconductor structure 104is a surface of the N-type semiconductor layer 104 b. The carbonnanotube 102 is located on the surface of the P-type semiconductor layer104 a, the transparent conductive film 106 is located on the surface ofthe N-type semiconductor layer 104 b. Referring to FIG. 3, in anotherembodiment, the first surface 1042 of the semiconductor structure 104 isthe surface of the N-type semiconductor layer 104 b, the second surface1044 of the semiconductor structure 104 is the surface of the P-typesemiconductor layer 104 a. The carbon nanotube 102 is located on thesurface of the N-type semiconductor layer 104 b, the transparentconductive film 106 is located on the surface of the P-typesemiconductor layer 104 a. A material of the P-type semiconductor layer104 a or the N-type semiconductor layer 104 b can be inorganic compoundsemiconductors, elemental semiconductors or organic semiconductors, suchas gallium arsenide, silicon carbide, polysilicon, monocrystallinesilicon, naphthalene or molybdenum sulfide. In one embodiment, thematerial of the N-type semiconductor layer 104 b is Molybdenum sulfide(MoS₂), and the thickness of the N-type semiconductor layer 104 b isabout 2.6 nanometers; the material of the P-type semiconductor layer 104a is Tungsten selenide (Wse2), and the thickness of the P-typesemiconductor layer 104 a is 6 nanometers.

The transparent conductive film 106 is used as a front electrode of thesolar battery 100. A material of the transparent conductive film 106 canbe metal, conductive polymer or ITO. The transparent conductive film 106is directly deposited on or coated on the second surface 1044 of thesemiconductor structure 104. A method of depositing the transparentconductive film 106 on the first surface 1044 of the semiconductorstructure 104 is not limited, and can be ion sputtering or magnetronsputtering. A thickness of the transparent conductive film 106 is notlimited, and can be in a range from 5 nanometers to 100 micrometers. Insome embodiments, the thickness of the transparent conductive film 106is in a range from 5 nanometers to 100 nanometers. In other embodiments,the thickness of the transparent conductive film 106 is in a range from5 nanometers to 20 nanometers. A shape of the transparent conductivefilm 106 is not limited, and can be bar, linear, square, or the like. Inone embodiment, the transparent conductive film 106 is strip-shaped.

A multi-layered stereoscopic structure 110 is formed by the carbonnanotube 102, the semiconductor structure 104 and the transparentconductive film 106. A cross-sectional area of the multi-layeredstereoscopic structure 110 is determined by the carbon nanotube 102.Because the carbon nanotube 102 is in nanoscale, an the cross-sectionalarea of the multi-layered stereoscopic structure 110 is nanoscale. Themulti-layered stereoscopic structure 110 defines a first cross-sectionalsurface and a second cross-sectional surface. The first cross-sectionalsurface is parallel with the surface of the semiconductor structure 104.The second cross-sectional surface is perpendicular with the surface ofthe semiconductor structure 104. That is, the first cross-sectionalsurface is perpendicular with the second cross-sectional surface. Anarea of the first cross-sectional surface is determined by the diameterof the carbon nanotube 102 and a thickness of the multi-layeredstereoscopic structure 110. An area of the second cross-sectionalsurface is determined by the length of the carbon nanotube 102 and thethickness of the multi-layered stereoscopic structure 110. In oneembodiment, the cross-sectional area of the multi-layered stereoscopicstructure 110 ranges from about 0.25 nm² to about 1000 nm². In anotherembodiment, the cross-sectional area of the multi-layered stereoscopicstructure 110 ranges from about 1 nm² to about 100 nm².

A Wan der Waals heterostructure is formed by the multi-layeredstereoscopic structure 110 between the carbon nanotube 102, thesemiconductor structure 104 and the transparent conductive film 106. Inuse of the solar battery 100, a Schottky junction is formed between thecarbon nanotube 102, the semiconductor structure 104 and the transparentconductive film 106 in the multi-layered stereoscopic structure 110. Thecarbon nanotube 102 and the transparent conductive film 106 can beregarded as two electrodes located on surfaces of the semiconductorstructure 104. The semiconductor structure 104 is a P-N junction. Whensunlight gets through the transparent film 106 and is emitted on thesemiconductor structure 104, a current can get through the multi-layeredstereoscopic structure 110. The current flows along the multi-layeredstereoscopic structure 110. A working part of the solar battery 100 ismulti-layered stereoscopic structure 110. As such, a size of the solarbattery 100 is larger than or equal to the multi-layered stereoscopicstructure 110. As such, the solar battery 100 is in nanoscale.

Referring to FIG. 4, a solar battery 200 according to one embodiment isprovided. The solar battery 200 includes a first electrode 202, a secondelectrode 204, a solar battery 100, a gate electrode 208, an insulatinglayer 210 and a solar cell 206. The solar cell 206 is electricallyconnected to the first electrode 202 and the second electrode 204. Thegate electrode 208 is insulated from the solar cell 206, the firstelectrode 202 and the second electrode 204 through the insulating layer210. Characteristics of the solar cell 206 is the same as that of thesolar battery 100 discussed before. The solar battery 200 can include aplurality of solar cell 206.

In the solar battery 200, the gate electrode 208 and the insulatinglayer 210 are stacked, and the solar cell 206 is located on a surface ofthe insulating layer 210, the insulating layer 210 is located betweenthe gate electrode 208 and the solar cell 206. In the solar cell 206,the carbon nanotube 102 are directly located on the surface of theinsulating layer 210, the semiconductor structure 104 is located abovethe carbon nanotubes 102, the carbon nanotubes 102 are located betweenthe semiconductor structure 104 and the insulating layer 210, and thetransparent conductive film 106 is located above the semiconductorstructure 104.

The first electrode 202 and the second electrode 204 are made ofconductive material, such as metal, Indium Tin Oxides (ITO), AntimonyTin Oxide (ATO), conductive silver paste, carbon nanotubes or any othersuitable conductive materials. The metal can be aluminum, copper,tungsten, molybdenum, gold, titanium, palladium or any combination ofalloys. In one embodiment, the first electrode 202 and the secondelectrode 204 are both conductive films. A thickness of the conductivefilm ranges from about 2 microns to about 100 microns. In thisembodiment, the first electrode 202 and the second electrode 204 aremetal composite structures of Au and Ti. Specifically, the metalcomposite structure includes an Au layer and a Ti layer overlapped witheach other. The Ti layer has a thickness of 5 nm and the Au layer has athickness of 50 nm. In this embodiment, the first electrode 202 iselectrically connected to the carbon nanotube 102 and located at one endof the carbon nanotube 102 and adhered to the surface of the carbonnanotube 102. The Ti layer is located on the surface of the carbonnanotube 102, the Au layer is located on a surface of the Ti layer. Thesecond electrode 204 is electrically connected to the transparentconductive film 106 and located on one end of the transparent conductivefilm 106 and adhered on the surface of the transparent conductive film106, wherein the Ti layer is located on the surface of the transparentconductive film 106, the Au layer is located on the surface of the Tilayer.

The insulating layer 210 is made of an insulating material and has athickness of 1 nanometer to 100 micrometers. The insulating layer 210provides the insulation between the carbon nanotubes 102 and the gateelectrode 208. In this embodiment, the material of the insulating layer210 is silicon oxide.

The gate electrode 208 is made of a conductive material. The conductivematerial may be selected from the group consisting of metal, ITO, ATO,conductive silver paste, conductive polymer, and conductive carbonnanotube. The metallic material may be aluminum, copper, tungsten,molybdenum, gold, titanium, palladium or any combination of alloys. Inthis embodiment, the gate electrode 208 is a layered structure, theinsulating layer 210 is located on the surface of the gate electrode208. The first electrode 202, the second electrode 204, and the solarcell 206 are located on the insulating layer 210, and are supported bythe gate electrode 208 and the insulating layer 210. In the presentdisclosure, the carbon nanotube 102 are directly located on the surfaceof the insulating layer 210, the carbon nanotube 102 are close to thegate electrode 208, the transparent conductive film 106 is far away fromthe gate electrode 208. As such, the transparent conductive film 106will not generate shielding effect between the semiconductor structure104 and the gate electrode 208, and the gate electrode 208 can be usedto control the solar cell 206 when the solar battery 200 is used.

In the solar battery 200 provided by the present disclosure, the carbonnanotubes 102 are directly located on the insulating layer 210 as thebottom electrode and separated from the gate electrode 208 as the gateelectrode by only one insulating layer 210, due to special properties ofthe carbon nanotube 102, the conduction of the solar battery 200 can beregulated by the gate electrode 208, so that the solar battery 200exhibits asymmetric output characteristics. In this embodiment, thecarbon nanotubes 102 are located on the surface of the N-typesemiconductor layer 104 b, the transparent conductive film 106 islocated on the surface of the P-type semiconductor layer 104 a, and theP-type semiconductor layer 104 a is WSe₂ with a thickness of 6 nm. TheN-type semiconductor layer 104 b is MoS₂ with a thickness of 2.6 nm.

When the solar battery 200 provided by the present disclosure isapplied, the sunlight is radiated to the semiconductor structure 104through the transparent conductive film 106. Due to the van der Waalsheterostructure formed between the semiconductor structure 104, thecarbon nanotube 102 and the transparent conductive film 106, aphotovoltaic effect can be generated, and light energy is converted intoelectricity energy. Due to a special geometry and band structure ofcarbon nanotubes, the Fermi level of carbon nanotubes is more easilymodulated by a gate voltage. Therefore, the solar battery 200 using thecarbon nanotube 102 as a back electrode exhibits unique and excellentperformance.

It is to be understood that the above-described embodiments are intendedto illustrate rather than limit the present disclosure. Variations maybe made to the embodiments without departing from the spirit of thepresent disclosure as claimed. Elements associated with any of the aboveembodiments are envisioned to be associated with any other embodiments.The above-described embodiments illustrate the scope of the presentdisclosure but do not restrict the scope of the present disclosure.

Depending on the embodiment, certain of the steps of a method describedmay be removed, others may be added, and the sequence of steps may bealtered. The description and the claims drawn to a method may includesome indication in reference to certain steps. However, the indicationused is only to be viewed for identification purposes and not as asuggestion as to an order for the steps.

What is claimed is:
 1. A solar battery comprising: a first electrode, asecond electrode, a solar cell, an insulating layer and a gateelectrode, wherein the solar cell is electrically connected to the firstelectrode and the second electrode, the gate electrode is insulated fromthe solar cell, the first electrode and the second electrode through theinsulating layer, the solar cell comprises: a semiconductor structurecomprising a P-type semiconductor and an N-type semiconductor overlappedwith each other and defining a first surface and a second surface; asingle carbon nanotube located on the first surface of the semiconductorstructure and there is no other carbon nanotubes located on the firstsurface; a transparent conductive film located on the second surface ofthe semiconductor structure, wherein the transparent conductive film isformed on the second surface by a depositing method or a coating method,the semiconductor structure is located between the carbon nanotube andthe transparent conductive film, and the carbon nanotube, thesemiconductor structure and the transparent conductive film are stackedwith each other to form a multi-layered stereoscopic structure.
 2. Thesolar battery of claim 1, wherein the carbon nanotube is a metalliccarbon nanotube.
 3. The solar battery of claim 2, wherein the carbonnanotube is a single-walled carbon nanotube, and the diameter of thecarbon nanotube is in a range from about 1 nanometer to about 5nanometers.
 4. The solar battery of claim 1, wherein a thickness of thesemiconductor structure is in a range from about 1 nanometer to about200 nanometers.
 5. The solar battery of claim 1, wherein a material ofthe P-type semiconductor or the N-type semiconductor is galliumarsenide, silicon carbide, polysilicon, monocrystalline silicon,naphthalene or molybdenum sulfide.
 6. The solar battery of claim 1,wherein the transparent conductive film is directly formed on the secondsurface by the depositing method, and the depositing method comprisesion sputtering or magnetron sputtering.
 7. The solar battery of claim 1,wherein a thickness of the transparent conductive film is in a rangefrom 5 nanometers to 20 nanometers.
 8. The solar battery of claim 1,wherein a cross-sectional area of the multi-layered stereoscopicstructure is in a range from about 0.25 nm² to about 1000 nm².
 9. Thesolar battery of claim 8, wherein the cross-sectional area of themulti-layered stereoscopic structure is in a range from about 1 nm² toabout 100 nm².
 10. The solar battery of claim 1, wherein the firstsurface of the semiconductor structure is a surface of the P-typesemiconductor layer, the second surface of the semiconductor structureis a surface of the N-type semiconductor layer.
 11. The solar battery ofclaim 1, wherein the first surface of the semiconductor structure is thesurface of the N-type semiconductor layer, the second surface of thesemiconductor structure is the surface of the P-type semiconductorlayer.
 12. The solar battery of claim 1, wherein the first electrode iselectrically connected with the carbon nanotube, the second electrode iselectrically connected with the transparent conductive film.
 13. Thesolar battery of claim 1, wherein the carbon nanotube is directlylocated on a surface of the insulating layer.
 14. The solar battery ofclaim 1, wherein the carbon nanotube is a back electrode, thetransparent conductive film is a front electrode.